Question

Describe in detail the action of glucagon. Be sure to include a description of what it is (what kind of biomolecule/class of hormone), how its secretion is regulated, where specifically it is secreted from, its general effects on body cells, and finally each of its specific effects (if it has any) on: skeletal muscle, the liver, adipose tissue, and blood glucose levels.

Answer 1

Glucagon is a peptide hormone produced by alpha cells of pancreas, which helps in maintaining glucose hemostasis. The pancreas release glucagon when the insulin levels or blood glucose levels are low, on the other hand raised levels of glucose in blood or insulin inhibits the release of glucagon.

The release of glucagon is stimulated by low levels of glucose in blood, protein rich meals, and a hormone like adrenaline, the release of glucagon is inhibited by high levels of glucose in blood and carbohydrate rich meals.

In liver : Glucagon acts on the liver to convert glycogen, (which is stored form of glucose) to glucose, which is than released into the blood stream, this process is known as Glycogenolysis. Glucagon also acts on the liver by reducing the consumption of glucose by the liver cells, so that glucose can be secreted back into the blood, in addition to this it promotes the production of glucose from amino acid, this process is known as Gluconeogenisis.

Adipose tissue : Glucagon enhances the lipolysis of triglycerides in adipose tissue, this process conserves glucose levels by providing fatty acids as fuel to many cells.

Skeletal muscle : Glucagon does not have significant effect on skeletal muscles, but however released fatty acids from the adipose tissue can be catabolised and used as source of energy by the skeletal muscles.